heater control problems

i have a 2001 chevy silverado that has a problem with the heater/ac switch when you try to switch from heat to ac you still get hot air from the vents, but when you start the truck on a hot day and need ac you get cold air. any ideas? 

Is the truck running in both cases?  Did you switch off the AC control button? 

I have noticed a similar problem on my 2000 GMC Sierra.  When the
heater is on and the tempature gets warm in the truck, turning down the
temperature dial doesn't change the temperature of the heat coming
out.  I notice that if I stop the truck and later restart it, then
it works properly for awhile.



Did you find a solution to your problem, or has anyone else figured it out?

Might also suggest checking the compressor relay.   Have someone listen to see if the compressor is kicking in.   Just so you both know, your problem is within the cooling systems, not in the switch.

I have a 2001 Silverado with the same heater problem. The AC works just fine in the summer or winter, but as soon as you turn the control knob to heat, the temperature seems to stick on heat. You can move the control knob back to cool, but until the truck sits for about 10-20 minutes shut off, hot air continues to come out of the vents.

Has anyone found a resolution yet?

I dug into my heater problem this weekend, and found the problem to be a bad heater actuator GM #52474810. Once I pulled the actuator out, I did a quick search on the part number, and found many other people with the same problem. The fix has been documented many times, and here is one link that pretty much sums it all up! I hope this helps! Fairly easy fix, just one difficult screw to get out. You'll want to have a deep wall 7mm socket for this.

 http://www.****/forums/showthread.php?t=155993